Controlling Azimuthal Uniformity of Etch Process in Plasma Processing Chamber

ABSTRACT

Apparatus, systems, and methods for controlling azimuthal uniformity of an etch process in a plasma processing chamber are provided. In one embodiment, a plasma processing apparatus can include a plasma processing chamber and an RF cage disposed above the plasma processing chamber. A dielectric window can separate the plasma processing chamber and the RF cage. The apparatus can include a plasma generating coil disposed above the dielectric window. The plasma generating coil can be operable to generate an inductively coupled plasma in the plasma processing chamber when energized. The apparatus further includes a conductive surface disposed within the RF cage proximate to at least a portion of the plasma generating coil. The conductive surface is arranged to generate an azimuthally variable inductive coupling between the conductive surface and the plasma generating coil when the plasma generating coil is energized.

PRIORITY CLAIM

This application claims the benefit of priority of U.S. ProvisionalPatent Application Ser. No. 62/135,437, which is incorporated herein byreference for all purposes.

FIELD

The present disclosure relates to processing a substrate using a plasmasource.

BACKGROUND

Plasma processing is widely used in the semiconductor industry fordeposition, etching, resist removal, and related processing ofsemiconductor wafers and other substrates. Plasma sources (e.g.,microwave, ECR, inductive, etc.) are often used for plasma processing toproduce high density plasma and reactive species for processingsubstrates. RF plasma sources can be used in modern plasma etchapplications because of the ability of the RF plasma source to generatea process chemistry out of feed gases, and to provide an isotropic orhighly anisotropic etch at high or low etch rates. Plasma processingtools can be able to sustain a stable plasma in very different gases andunder very different conditions (gas flow, gas pressure, etc.) and canprovide for independent control of plasma density, plasma profile andion energy.

Requirements for process equivalence across, for instance, an entiresemiconductor wafer, from wafer to wafer in an etch chamber (and/or etchhead), from etch chamber to etch chamber across a tool, from etch toolto etch tool across a fabrication facility, or for every fabricationfacility across the world can lead to strict requirements for plasmaprocess uniformity in the processing of semiconductor wafers and othersubstrates. As a result, many plasma processing tools have processcontrols to compensate for non-uniformities in gas flow, plasma density,and other plasma process parameters. To meet stringent processingrequirements for radial process uniformity, some manufacturers employ avariety of methods and systems, such as multiple-coil inductively coupleplasma (ICP) sources or multi-zone capacitively coupled plasma (CCP)sources for plasma radial profile control, electrostatic chucks withmultiple radial temperature zones, multiple gas injections, etc.

To achieve uniformity in azimuthal direction, some manufacturers designand build plasma chambers, plasma generating parts (e.g., coils,electrodes), electrostatic chucks (ESCs), gas injections and gasexhausts, focus rings, and other components as symmetric as possible tomatch the symmetry of the semiconductor wafer or other substrate. Forthis reason, some powered elements (e.g., capacitors) are screened fromthe antenna and the plasma by placing them outside of the main RF cagein additional enclosures. Wafer placement is also controlled with highprecision. Moreover, the magnetic field of the Earth can also affectazimuthal uniformity depending on the location of the tool. Forinstance, in some cases, the magnetic field of the Earth can affectazimuthal process uniformity for different tools in the same room if thetools face different directions. Some manufacturers wrap champers withmagnetic shields to reduce these effects.

In many cases, higher uniformity requirements lead to higher costs ofthe plasma processing tool. For example, a 1% non-uniformity requirementcan require much more design efforts, additional controlling elements,more precise manufacturing of the parts and their assembly, etc. than a3% non-uniformity requirement. However, imperfection can occur in thedesign, manufacturing and/or assembly of the process tools.Imperfections in the design can lead to systematic non-uniformities.Imperfections in a manufactured part can lead to both systematic andrandom (e.g., one tool to another) non-uniformities. Imperfections inassembly can lead to random non-uniformities. When a tool is assembledand all parts are placed in their positions, these non-uniformities arecombined together and in the worst case they add to each other ratherthan compensate each other.

Most of the resulting radial non-uniformity can be compensated by tuningthe process using available control “knobs” (powers, temperatures of ESCzones, process time, etc.), but there is no control “knob” for tuningthe process in azimuthal direction. So if azimuthal non-uniformity orazimuthal head-to-head mismatch exceeds an acceptable limit, then theonly way to fix it, is to identify and replace parts with the largestcontribution to azimuthal non-uniformity This procedure can be expensiveand time consuming, leading to increased final production cost andincreased price of the tool. In some cases, the parts that are replacedmay not be bad parts at all and in combination with different otherparts the overall non-uniformity of the tool could be below that limit.

The number of elements in and around a plasma processing chamberaffecting plasma and process uniformity is quite large. These parts caninclude, for instance, a gas injection and gas outlet, coils, a pedestalwith bias electrode, and an electrostatic chuck (ESC), an RF cage,chamber walls and the door for wafer transfer, ESC feed structure,magnetic field from earth and from elements of the structure—frame,screws, turbo pump, cooling fans, and other elements. Contribution toasymmetry from some of these parts can be made very small. Howevercomponents such as ESC and coils cannot be made absolutely symmetric.For instance, the ESC can have a complicated structure with a number ofelectrodes, heating elements and cooling channels, bonding betweendifferent layers, etc. Coils can have leads and transitions from oneturn to another. One may decrease the magnitude of non-uniformityassociated with coil leads, by increasing number of leads and spreadingthe leads around (e.g., 3 one-turn coils oriented 120 degrees relativeto each other instead of one 3 turn coil, or two 1.5 turn coils havingleads on the opposite sides, etc.). However, this may lead to additionalcosts and may not provide for improved azimuthal uniformity.

One approach for addressing azimuthal non-uniformity is to provide forthe tilting of the coil as a whole, with respect to the wafer (and/orthe pedestal). However, this solution may not be practical because itcan cause a very strong effect and cannot be used for fine tuning whenthe azimuthal non-uniformity is already small.

SUMMARY

Aspects and advantages of embodiments of the present disclosure will beset forth in part in the following description, or may be learned fromthe description, or may be learned through practice of the embodiments.

One example aspect of the present disclosure is directed to a plasmaprocessing apparatus. The plasma processing apparatus can include aplasma processing chamber, an RF cage disposed above the plasmaprocessing chamber, and dielectric window separating the plasmaprocessing chamber and the RF cage. The plasma processing apparatus canfurther include a plasma generating coil disposed above the dielectricwindow. The plasma generating coil can be operable to generate aninductively coupled plasma in the plasma processing chamber whenenergized. The plasma processing apparatus can include a conductivesurface disposed within the RF cage proximate to at least a portion ofthe plasma generating coil. The conductive surface can be so disposed asto generate an azimuthally variable inductive coupling between theconductive surface and the plasma generating coil when the plasmagenerating coil is energized.

Another example embodiment of the present disclosure is directed to amethod for adjusting azimuthal process uniformity in a plasma processingapparatus. The method can include processing a semiconductor substratein a plasma processing apparatus using a plasma etch process. The plasmaprocessing apparatus can include a plasma processing chamber, an RF cagedisposed above the plasma processing chamber, a dielectric windowseparating the plasma processing chamber and the RF cage, and a plasmagenerating coil disposed above the dielectric window. The method canfurther include analyzing data associated with an azimuthal profileassociated with the plasma etch process. The method can includeadjusting a conductive surface disposed within the RF cage proximate toat least a portion of the plasma generating coil to generate anazimuthally variable inductive coupling between the conductive surfaceand the plasma generating coil.

Yet another example embodiment of the present disclosure is directed toa plasma processing apparatus. The plasma processing apparatus caninclude a plasma processing chamber having an interior operable toconfine a process gas, an RF cage disposed above the plasma processingchamber, and a dielectric window. The plasma processing apparatus canfurther include one or more inductive elements operable to generate aninductively coupled plasma in the plasma processing chamber whenenergized with RF energy. The plasma processing apparatus can includeone or more conductive surfaces disposed within the RF cage proximate toat least a portion of the one or more inductive elements. At least aportion of the one or more conductive surfaces can be movable relativeto the one or more inductive elements so as to generate one or moreazimuthally variable inductive couplings between the one or moreconductive surfaces and the one or more inductive elements when the oneor more inductive elements are energized with RF energy.

Other example aspects of the present disclosure are directed to systems,methods, devices, and processes for controlling azimuthal uniformity ina plasma etch process.

These and other features, aspects and advantages of various embodimentswill become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the present disclosure and, together with thedescription, serve to explain the related principles.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed discussion of embodiments directed to one of ordinary skill inthe art are set forth in the specification, which makes reference to theappended figures, in which:

FIG. 1 depicts aspects of an example plasma processing apparatusaccording to example embodiments of the present disclosure;

FIG. 2 depicts aspects of an example conductive surface according toexample embodiments of the present disclosure;

FIG. 3 depicts aspects of an example partial conductive surfaceaccording to example embodiments of the present disclosure;

FIG. 4 depicts aspects of an example plasma processing apparatus thatincludes a conductive surface with one or more conductive wire(s)according to example embodiments of the present disclosure;

FIG. 5 depicts aspects of an example conductive element placement andoperation with cylindrical plasma energizing coil according to thepresent disclosure;

FIG. 6 depicts aspects of an example plasma processing apparatusaccording to example embodiments of the present disclosure;

FIG. 7 depicts aspects of an example plasma processing apparatusaccording to example embodiments of the present disclosure;

FIG. 8 depicts a flow diagram of an example method for adjustingazimuthal process uniformity in a plasma processing apparatus accordingto example embodiments of the present disclosure; and

FIG. 9 depicts aspects of an example azimuthal profile according toexample embodiments of the present disclosure.

DETAILED DESCRIPTION

A key requirement for any control is a predictable, monotonic responseand not over-sensitivity of the output to the variation of the input.That means predictability and repeatability. For example, if the etchrate dependence on the bias power was too strong, then process resultswould not be repeatable—any small fluctuation of bias power would changethe rate, making bias difficult to use.

The common difficulty with controlling azimuthal non-uniformity is thatall parts are symmetric by design, but typically asymmetric elementsaffect azimuthal profile. According to example aspects of the presentdisclosure, a new element can be introduced that can easily be changedfrom symmetric to a controlled asymmetric, so that if corrective actionis required, one can easily make a desired change in this element.

Reference now will be made in detail to embodiments, one or moreexamples of which are illustrated in the drawings. Each example isprovided by way of explanation of the embodiments, not limitation of thepresent disclosure. In fact, it will be apparent to those skilled in theart that various modifications and variations can be made to theembodiments without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that aspects of the presentdisclosure cover such modifications and variations.

To be more specific, example aspects of the present disclosure aredirected to a conductive surface/RF shield disposed above the coil of aplasma process chamber at some distance from the coil, separating thecoil from all other elements in the RF cage (e.g., capacitors, etc.).The coil can be an antenna, which “communicates” not only with theplasma, but with everything else proximate to the coil. Placing theshield and separating the coil from all other elements in the RF cagecan cut off all undesirable “communications” between the coil and thoseelements and replace those communications with a single “communication”to the shield. In some implementations, grounding of this shield can bebeneficial since it can remove stray capacitive and/or other couplingthat the coil and/or the plasma might have with other elements insidethe RF cage.

If the shield is placed in such a way that the coil is only slightlycoupled (e.g., inductively) to the shield compared to a strong couplingto the plasma, then the power that the shield takes from the coil can besmall and the effect of the shield on the process can be small.Controlling the distance between different parts of the coil and theshield can generate a small asymmetric, disturbance to the couplingbetween the coil and the plasma, and to the process, which depends onthis coupling.

Example aspects of the present disclosure are directed to apparatus,systems, and methods for controlling azimuthal uniformity of etchprocesses in plasma processing chambers. As indicated herein, theadjustment of the distance between the conductive surface and differentazimuthal portions of the coil can provide an effective controlparameter for control of azimuthal process uniformity. For instance, inone embodiment, the conductive surface can include a ring shaped shield.Bending or tilting the shield toward the coil in a particular azimuthalarea can reduce coil-to-plasma power transfer in that azimuthal area.Bending or tilting the shield away from the coil in a particularazimuthal area can reduce coil-to-shield coupling, and thus improvecoil-to-plasma power transfer in that azimuthal area.

Since the power coupled to the shield is small, the correction to theplasma process due to this action can also be small. For instance,without being bound by any particular theory of operation, when one sideof the shield gets closer to or farther from the coil, it affects thecurrent in the coil everywhere. In other words it has no azimuthaleffect on the current in the coil. However, the current induced in theshield by the coil flows at different distance from plasma, and affectsdifferently the field in plasma. This effect is secondary. As a result,the second order effect it generates in plasma is also small, whichmakes it useful for control. Not bending or tilting the shield willgenerate a small, but uniform reduction of power transfer from the coilto the plasma. Thus, the result of this action can be predictable,monotonic and small and hence this kind of azimuthal process control cansatisfy such requirements.

This process for controlling azimuthal uniformity can be especiallyeffective in circumstances when neither design nor parts manufacturingor tool assembly generate systematic azimuthal non-uniformity, butrather the final non-uniformity is caused by a number of random factorsand is difficult to predict. In these circumstances, every processingchamber may need individual correction, and the required correction maybe small.

Controlling azimuthal uniformity according to example embodiments of thepresent disclosure can reduce azimuthal non-uniformity of the processresult on the semiconductor wafer or other substrate, for instance fromabout 1.5% to less than about 0.5%, and quickly one head to anotherusing simple procedure. As used herein, the use of the term “about” whenused in conjunction with a numerical value refers to within about 35% ofthe stated amount. In some implementations, example aspects of of thepresent disclosure can be used to reduce azimuthal non-uniformity fromabout 1.5% to approximately 0.2-0.5%, and to quickly match processingheads and chambers using simple procedures. Some processes can lead toheads with the same azimuthal uniformity.

Moreover, the process of reducing azimuthal non-uniformity according toexample aspects of the present disclosure can be relativelystraightforward. First, after processing semiconductor wafers andachieving a desired radial profile, the azimuthal profile can beanalyzed to identify maximums and minimums. In many cases the maximumsand minimums can be identified near the edge of the plasma processingprofile, where maximums and minimums are more pronounced. The distanceof an RF shield relative to the coil can then be adjusted to change theazimuthal profile of the process. For instance, an edge of the shieldcan be lifted up away from a coil at azimuthal locations where ICP powerto plasma needs to be increased. An edge of the shield can be moved downcloser to the coil at azimuthal locations where ICP power to plasmaneeds to be decreased. It can take just one or two iterations to achievea desired uniformity/profile.

Adjusting the distance of an edge of an RF shield relative to a coil canprovide flexibility in addressing both random and systematic azimuthalnon-uniformities. Other methods for adjusting the distance of aconductive surface relative to a coil to address azimuthalnon-uniformities can be used without deviating from the scope of thepresent disclosure. For instance, in some embodiments, partial shieldsdisposed proximate to only a select azimuthal portion of the coil can beused to address more systematic azimuthal non-uniformities. In someembodiments, if a plasma source has a plurality of coils, then aplurality of shields can be disposed relative to the plurality of coilsto address azimuthal non-uniformities. In some embodiments, instead ofbending down, the shield may include a flexible section (e.g., a wire)attached to the shield. The flexible section can slack down toward thecoil creating an effect similar to bending down the shield.

With reference now to the Figures, example embodiments of the presentdisclosure will now be discussed in detail. FIG. 1 depicts aspects of anexample plasma processing apparatus 100 according to example embodimentsof the present disclosure. FIG. 1 illustrates cross-sectional view ofthe plasma processing apparatus 100. The plasma processing apparatus 100can include a plasma processing chamber 102, an RF cage 104, adielectric window 106, an inductive element 108, and a conductivesurface or shield 110.

The processing chamber 102 can define an interior space 112. A pedestalor substrate holder 114 can be used to support a substrate 116, such asa semiconductor wafer, within the interior space 112. In someimplementations, feed gas can be introduced into the processing chamber102 through one or more feed gas hole(s) 118 in a wall. The feed gashole(s) 118 can receive process gas through tubulations such as, forexample, one or more feed gas conduit(s) 120. The location andorientation of feed gas hole(s) 118 and/or feed gas conduit(s) 120 shownin FIG. 1 are not intended to be limiting. The plasma processingapparatus 100 can be configured to include feed gas hole(s) 118 and/orfeed gas conduit(s) 120 in other locations and orientations (e.g.,dielectric window 106) and still properly provide feed gas to plasmaprocessing apparatus 100. For instance, in some implementations, feedgas can be provided via feed gas hole(s) in the dielectric window orthrough a showerhead.

Each of the feed gas conduit(s) 120 and/or feed hole(s) 118 can beconfigured to admit a preselected flow rate of feed gas to interiorspace 112. These flow rates can be adjusted based on desired processingparameters. For instance, the control of various flow rates of feed gasfrom different feed gas conduit(s) into interior space 112 can providefor the efficient and separate tuning of the spatial distribution ofcharged and neutral species generated in the process gas during plasmaprocessing.

The RF cage 104 can be disposed above the plasma processing chamber 102.The RF cage 104 can be formed by conductive material or by a mesh ofsuch material and can be grounded to reduce the radiation ofelectromagnetic interference into the surrounding environment, as wellas shield its interior (and/or the component enclosed therein) fromexternal electromagnetic radiation. For example, the RF cage 104 can beconfigured to enclose the inductive element 108, as well as theconductive surface 110. Placing the conductive surface 110 and theinductive element 108 in the RF cage 104 can reduce undesirableinterference between the inductive element 108 and other elements placedabove the conductive surface 110 in the RF cage 104, thereby furtherfacilitating inductive coupling between the inductive element 108 andthe conductive surface 110 when the inductive element 108 is energized.

In some implementations, the dielectric window 106 can separate theplasma processing chamber 102 and the RF cage 104. For instance, thedielectric window 106 can be located above the substrate holder 114. Thedielectric window 106 can be a window positioned near the inductiveelement 108, through which a substantial portion of the magnetic fluxlines from the inductive element 108 enter and/or return from the plasmaprocessing chamber 102. The dielectric window 106 can include materialssuch as quartz, ceramic, etc. It will be understood that the dielectricwindow 106 can be configured in various different ways. For example, asshown in FIG. 1, the dielectric window 106 can span an entire uppersurface of a chamber and be supported by mechanical bonding.

The inductive element 108 can be disposed above the dielectric window106. For instance, the inductive element 108 can include a plasmagenerating coil (and/or an antenna element) that when supplied with RFpower, induces a plasma in the process gas in the interior space 120 ofthe plasma processing apparatus 100. For instance, an RF generator 120can be configured to provide electromagnetic energy through a matchingnetwork 122 to the inductive element 108. The inductive element 108(e.g., plasma generating coil) can be operable to generate aninductively coupled plasma 124 in the plasma processing chamber 102 whenenergized.

The conductive surface 110 can be disposed within the RF cage 104proximate to at least a portion of the inductive element 108. Theconductive surface 110 can be, for example, an RF shield. In someimplementations, at least a portion of a peripheral edge of theconductive surface 110 can be retained in one or more grooves 126located in a sidewall 128 of the RF cage 104. Additionally, and/oralternatively, at least a portion of the peripheral edge of theconductive surface 110 can be retained by one or more pins 130 disposedin a sidewall 128 of the RF cage 104.

The conductive surface 110 can be configured to separate the inductiveelement 108 (e.g., coil) from other elements (e.g., capacitors, etc.) inthe RF cage 104. For example, the inductive element 108 can act as anantenna that electromagnetically couples (e.g., “communicates”), notonly with the plasma 124, but with other components proximate to theinductive element 108. The conductive surface 110 can be configured toreduce undesirable electromagnetic coupling between the inductiveelement 108 and those other components, and replace such coupling withelectromagnetic coupling between the conductive surface 110 and theindicative element 108. As indicated above, in some implementations, theconductive surface 110 can be grounded to reduce capacitive couplingthat the indicative element 108 might have with the other components inthe RF cage 104. Moreover, the conductive surface 110 can be arranged insuch a way that the inductive element 108 is only slightly coupled(e.g., inductively) to the conductive surface 110 compared to a strongercoupling to the plasma 124. The power the conductive surface 110 takesfrom the inductive element 108 can be relatively small and the generaleffect of the conductive surface 110 on the plasma process can also besmall.

The conductive surface 110 can be configured in various shapes and/orsize(s). FIG. 2 depicts aspects of an example conductive surface 200according to example embodiments of the present disclosure. In someimplementations, the conductive surface 110 can have conductive shield200. As shown, the conductive shield 200 can include an annular shieldportion 201 and can be grounded. The conductive shield 200 can include acenter portion 202 (e.g., of the annular shield portion 201) that can beconfigured to be fixed relative to at least a portion of the inductiveelement 108 (e.g., plasma generating coil) and a peripheral edge 206. Asfurther described below, in some implementations conductive shield 200can include a flexible section 208 incorporated as a portion of and/orattached to the annular shield 201. In this way, in addition to and/orinstead of moving the peripheral edges 206 of the conductive surface200, the flexible section 208 can slack down toward the inductiveelement 108, thereby creating an effect similar to bending down theconductive surface 200, as described herein.

At least a portion of the conductive shield 200 can be movable relativeto the inductive element 108 (e.g., plasma generating coil). Forexample, at least a portion of the conductive shield 200 can be affixedto an adjustment mechanism 210 (e.g., arm and slot, telescopingmechanism). The adjustment mechanism 210 can be configured to tiltand/or bend at least a portion of the conductive shield 200 relative tothe inductive element 108.

For instance, at least a portion of the peripheral edge 206 of theannular shield 201 can be movable towards and/or away from the inductiveelement 108. The adjustment mechanism 210 can be configured to cause atleast the portion of the peripheral edge 206 to move towards and/or awayfrom the inductive element 108. The adjustment mechanism 210 can beconfigured to be controlled by a controller (not shown). The controllercan be configured to adjust the adjustment mechanism 210 (and theposition of at least a portion of the conductive surface 110) based oninput from a user and/or automatically, based, at least in part, on theprocess characteristics and/or the inductive coupling between theconductive surface 110 and the inductive element 108.

The shape of conductive shield 200 is not intended to be limiting. Theconductive surface 110 can include different shapes (e.g., square,rectangular, triangular, polygonal) than shown FIG. 2. Moreover, theconductive surface 110 can include irregular shapes. For instance, FIG.3 depicts aspects of an example conductive surface 300 according toexample embodiments of the present disclosure. The conductive surface300 can include a partial annular shield 302. In some implementations,the partial annular shield 302 can be grounded and/or can include one ormore wire(s) 304 that can be configured to close the loop of the partialannular shield 302, in order to create a current in the partial annularshield 302. In some implementations, the conductive surface 300 can bedisposed proximate to only a select azimuthal portion of the inductiveelement 108 (e.g., plasma generating coil). In this way, partial shieldsdisposed proximate to only a select azimuthal portion of the coil can beused to address more systematic azimuthal non-uniformities.

Returning to FIG. 1, the conductive surface 110 (e.g., which can includeconductive shield 200, 300, etc.) can be disposed so as to generate anazimuthally variable inductive coupling between the conductive surface110 and the inductive element 108 when the inductive element 108 isenergized. The azimuthally variable inductive coupling between theconductive surface 110 and the inductive element 108 (e.g., plasmagenerating coil) can be operable to generate an asymmetric disturbanceto an inductive coupling between the inductive element 108 and theinductively coupled plasma 124.

For instance, controlling the distance between different azimuthalportions of the inductive element 108 and the conductive surface 110 bytilting, bending, moving, etc. the conductive surface 110 can generatesmall asymmetric, disturbances to the coupling between the inductiveelement 108 and the plasma 124 (and to the plasma process which dependson the coupling). By way of example, at least a first azimuthal portion132 of the conductive surface 110 can be bent, tilted, moved, etc.(e.g., via adjustment mechanism 210) closer to the inductive element 108relative to a second azimuthal portion 134 of the conductive surface110. The first azimuthal portion 132 of the conductive surface 110 canbe located a first distance 136 from the inductive element 108 (e.g.,plasma generating coil) and the second azimuthal portion 134 of theconductive surface 110 can be located a second distance 138 from theinductive element 108. The second distance 138 can be different from thefirst distance 136.

The adjustment of the first and second distances 136, 138 betweendifferent azimuthal portions of the conductive surface 110 and differentazimuthal portions of the inductive element 108 can provide an effectivecontrol parameter for control of azimuthal process uniformity. Forinstance, bending or tilting the conductive surface 110 (e.g., firstazimuthal portion 132) toward the inductive element 108 in a particularazimuthal area can reduce inductive element-to-plasma power transfer inthat azimuthal area. Bending or tilting the conductive surface 110(e.g., second azimuthal portion 134) away from the inductive element 108in a particular azimuthal area can reduce inductiveelement-to-conductive surface coupling, and thus improve inductiveelement-to-plasma power transfer in that azimuthal area.

Since the power coupled to the conductive surface 110 can be small, thecorrection to the plasma process due to this action can also be small.For instance, when the first and/or second azimuthal portions 132, 134of the conductive surface 110 gets closer to or farther from theinductive element 108, it can affect the current in the inductiveelement 108 elsewhere. In some implementations, it can have no azimuthaleffect on the current in the inductive element 108. However, the currentinduced in the conductive surface 110 by the inductive element 108 canflow at different distances from the plasma 124, and can affectdifferently the field in the plasma 124. Accordingly, the effectgenerated in the plasma 124 can also be small, which makes it useful forcontrol. Not bending or tilting the conductive surface 110 can generatea small, but uniform reduction of power transfer from the inductiveelement 108 to the plasma 124.

In some implementations, the plasma processing apparatus can include oneor more conductive wire(s) that can be configured to create an effectsimilar to adjusting the conductive surface 110. FIG. 4 depicts aspectsof an example plasma processing apparatus 400 that includes theconductive surface 200 with one or more conductive wire(s) 408. Theconductive wire(s) 408 can be connected to the conductive surface 200.At least a portion of the conductive wire(s) 408 can be adjustable(e.g., via an adjustment mechanism not shown) to increase and/ordecrease a distance 402 between the conductive wire(s) 408 and theinductive element 108 (e.g., plasma generating coil). In this way, inaddition to and/or instead of moving the peripheral edges 206 of theconductive surface 200, the conductive wire(s) 408 can slack down towardthe inductive element 108, thereby creating an effect similar to bendingdown the conductive surface 200, as described above.

FIG. 5 depicts aspects of example conductive element placement andoperation with cylindrical plasma processing chamber 500 and cylindricalplasma energizing coil 518 according to example embodiments of thepresent disclosure. As illustrated, in this cross-sectional view, theplasma processing apparatus 500 can include a plasma chamber 504. Aninductive plasma can be generated in plasma chamber 504 (i.e., plasmageneration region).

The plasma chamber 504 can include a dielectric window 512. Dielectricwindow 512 can be formed from any dielectric material, such as quartz,ceramic, etc. An inductive element 518 (e.g., a plasma generating coil)can be disposed adjacent the dielectric window 512. The inductiveelement 518 can be coupled to an RF power generator through a suitablematching network (not shown). Reactant and carrier gases can be providedto the chamber interior from a gas supply (not shown). When theinductive element 518 is energized with RF power from the RF powergenerator, an inductive plasma can be induced in the plasma chamber 504.In some embodiments, the plasma reactor 500 can include a faraday shield524 that can be configured to reduce capacitive coupling of theinductive element 518 to the plasma. The plasma chamber 504 can includea conductive surface 526 disposed proximate to at least a portion of theinductive element 518. The conductive surface 526 and the inductiveelement 518 disposed within an RF cage 538. The RF cage 538 can beconfigured to reduce the radiation of electromagnetic interference intothe surrounding environment.

The conductive surface 526 can be configured to provide a similar effectas that described above with reference to the conductive surface 110 ofFIG. 1. For instance, in some implementations, conductive surface 526can be wrapped around the inductive element 518. By controlling thedistance between different azimuthal portions of the inductive element518 and the conductive surface 526, small asymmetric, disturbances tothe coupling between the inductive element 518 and the plasma (and tothe plasma process which depends on the coupling) can be generated. Byway of example, at least a first azimuthal portion 528 of the conductivesurface 526 can be bent, tilted, moved, etc. (e.g., via adjustmentmechanism 530) closer to the inductive element 518 relative to a secondazimuthal portion 532 of the conductive surface 526. The first azimuthalportion 528 can be located a first distance 534 from the inductiveelement 518 (e.g., plasma generating coil) and the second azimuthalportion 532 of the conductive surface 526 can be located a seconddistance 536 from the inductive element 518. The second distance 536 canbe different from the first distance 534.

FIG. 6 depicts a plasma processing apparatus 600 according to an exampleembodiment of the present disclosure. The plasma processing apparatus600 can include a plasma processing chamber 602 defining an interiorspace 604. A pedestal or substrate holder 606 can be used to support asubstrate 608 within the interior space 604. A dielectric window 610 canbe located above the substrate holder 606. The dielectric window 610 caninclude a relatively flat central portion 612 and an angled peripheralportion 614. The dielectric window 610 can include a space in thecentral portion 612 for a showerhead 616 to feed process gas into theinterior space 604.

The plasma processing apparatus 600 can include a plurality of inductiveelements, such as a plurality of plasma generating coils. For instance,the plasma processing apparatus 600 can include a first inductiveelement 618 and a second inductive element 620, for generating aninductive plasma in the interior space 604 (operable to confine aprocess gas). The inductive elements 618, 620 can include a plasmagenerating coil and/or antenna element that when supplied with RF power,induces a plasma in the process gas in the interior space 604 of theplasma processing apparatus 600. For instance, a first RF generator (notshown) can be configured to provide electromagnetic energy through amatching network to the first inductive element 618. A second RFgenerator (not shown) can be configured to provide electromagneticenergy through a matching network to the second inductive element 620.The first inductive element 618 and/or the second inductive element 620can be operable to generate an inductively coupled plasma in the plasmaprocessing chamber 602 when energized with RF energy.

In some implementations, the plasma processing apparatus 600 can furtherinclude a Faraday shield 624 disposed between the first inductiveelement 618 and the dielectric window 612. Faraday shield 624 can be aslotted metal shield that reduces capacitive coupling between the firstinductive element 618 and the interior space 604.

The plasma processing apparatus 600 can include an RF cage 626 disposedabove the plasma processing chamber 602. The RF cage 626 can be formedby conductive material or by a mesh of such material. The RF cage 626can be configured to reduce the radiation of electromagneticinterference into the surrounding environment.

The plasma processing apparatus 600 can include a plurality ofconductive surfaces. The conductive surfaces can be disposed within theRF cage 626, proximate to at least a portion of the first and secondinductive elements 618, 620. Each conductive surface can be associatedwith at least one of the plurality of inductive elements 618, 620.Additionally, and/or alternatively, each conductive surface can be sodisposed as to generate an azimuthally variable inductive couplingbetween the conductive surface and its associated inductive element whenthe inductive element is energized.

For example, plasma processing apparatus can include a first conductivesurface 628 and a second conductive surface 630. The first conductivesurface 628 can be associated with the first inductive element 618. Atleast a portion of the first conductive surface 628 can be can bemovable relative to the first inductive element 618 so as to generate afirst azimuthally variable inductive coupling between the firstconductive surface 628 and the first inductive element 618 when thefirst inductive element 618 is energized with RF energy. The secondconductive surface 630 can be associated with the second inductiveelement 620. At least a portion of the second conductive surface 630 canbe movable relative to the second inductive element 620 so as togenerate a second azimuthally variable inductive coupling between thesecond conductive surface 630 and the second inductive element 620 whenthe second inductive element 620 is energized with RF energy. In thisway, the first and second conductive surfaces 628, 630 can be configuredto generate a similar effect to that described above with reference toconductive surface 110 of FIG. 1.

In some implementations, a conductive surface can be associated with oneor more inductive elements. For example, FIG. 7 depicts aspects of anexample plasma processing apparatus 700 according to example embodimentsof the present disclosure. As shown, the plasma processing apparatus 700can include a first inductive element 702 and a second inductive element704. A conductive surface 706 (e.g., annular shield) can be disposedproximate to at least a portion of the first inductive element 702. Atleast a portion of the conductive surface 706 can be movable (e.g., viaadjustment mechanism 708) relative to the first inductive element 702.In this way, one or more azimuthally variable inductive couplings can becreated between the conductive surface 706 and the first inductiveelement 702, when the first inductive element 702, is energized with RFenergy. This process is similar to that described above with referenceto FIG. 1.

FIG. 8 depicts a flow diagram of an example method 800 for adjustingazimuthal process uniformity in a plasma processing apparatus accordingto example embodiments of the present disclosure. FIG. 8 can beimplemented by a plasma processing apparatus and/or the controlcomponents and computing devices associated therewith. While method 800is described below as being implemented by the plasma processingapparatus 100, method 800 can be implemented by any of the plasmaprocessing apparatuses 100, 400, 500, 600, 700 described herein. Inaddition, FIG. 8 depicts steps performed in a particular order forpurposes of illustration and discussion. Those of ordinary skill in theart, using the disclosures provided herein, will understand that thevarious steps of any of the methods disclosed herein can be modified,adapted, expanded, rearranged and/or omitted in various ways withoutdeviating from the scope of the present disclosure.

At (802), the method 800 can include processing a semiconductorsubstrate 116 (e.g., wafer) in a plasma processing apparatus 100 using aplasma etch process. For example, the plasma processing apparatus 100can include a plasma processing chamber 102, an RF cage 104 disposedabove the plasma processing chamber 102, a dielectric window 106separating the plasma processing chamber 102 and the RF cage 104, and aninductive element 108 (e.g., plasma generating coil) disposed above thedielectric window 106. When energized, the inductive element 108 caninduce a plasma through interaction with a process gas (e.g., in theinterior space 120) of plasma processing apparatus 100.

At (804), the method 800 can include analyzing data associated with anazimuthal profile associated with a plasma etch process. For instance,FIG. 9 depicts aspects of an example azimuthal profile 900 at someradius according to example embodiments of the present disclosure. Theazimuthal profile 900 can be indicative of the one or more processcharacteristic(s) (e.g., etch rate), relative to the azimuthal angle ofa plasma etch process at some fixed radius. The azimuthal profile caninclude one or more minimums and/or maximums. The minimums and/ormaximums can be identified near the edge of the plasma processingprofile, where minimums and/or maximums can be more pronounced. Forexample, as shown in FIG. 9, the azimuthal profile 900 can include amaximum 902 between a first azimuth angle Θ₁ and a second azimuth angleΘ₂. The azimuthal profile 900 can be analyzed (manually and/or by acomputing system) to identify, for example, a minimum and/or a maximum,such as the maximum 902 between the first azimuth angle Θ₁ and thesecond azimuth angle Θ₂.

At (806), the method 800 can include determining whether the conditionsof the desired azimuthal profile are satisfied. For instance, a userand/or one or more computing device(s) associated with the plasmaprocessing apparatus can determine whether the conditions of the desiredazimuthal profile are satisfied based, at least in part, on the dataassociated with the azimuthal profile. When the conditions are notsatisfied, the conductive surface can be adjusted at (808), as describedbelow. When the conditions are satisfied, at (810) the method 800 can becompleted. When the conditions are not satisfied, the method 800 can berepeated. In this way, the process can be implemented in one or moreiteration(s) to achieve a desired uniformity/profile.

At (808), the method 800 can include adjusting a conductive surface. Forinstance, the method 800 can include adjusting the conductive surface110 disposed within the RF cage 104 proximate to, at least a portion of,the inductive element 108 (e.g., plasma generating coil) to generate anazimuthally variable inductive coupling between the conductive surface110 and the inductive element 108. The conductive surface 110 can beadjusted based, at least in part, on one or more minimums or maximumsidentified in the data associated with the plasma etch process.

For instance, the distance of the conductive surface 110 relative to theinductive element 108 can be adjusted to change the azimuthal profile ofthe process. For instance, a peripheral edge of the conductive surface110 can be moved closer to the inductive element 108 at azimuthallocations between azimuth θ₁ and θ₂ where ICP power to plasma needs tobe decreased. Additionally, and/or alternatively, a peripheral edge ofthe conductive surface 110 can be lifted up (moved away) from theinductive element 108 at azimuthal locations outside azimuths θ₁ and θ₂where ICP power to plasma needs to be increased.

For example, the conductive surface 110 can be adjusted based, at leastin part, on the maximum 902 identified in the azimuthal profile 900.Adjusting the conductive surface 110 can include moving the firstazimuthal portion 132 of a peripheral edge of the conductive surface 110(e.g., peripheral edge 206 of conductive surface 200) closer to theinductive element 108 (e.g., plasma generating coil) relative to thesecond azimuthal portion 134 of the peripheral edge of the conductivesurface 110. The first azimuthal portion 132 of a peripheral edge of theconductive surface 110 can be moved farther away from the inductiveelement 108 relative to the second azimuthal portion 134 of theperipheral edge of the conductive surface 110. Such adjustment caninduce an effect, as described above with reference to FIG. 1.

In some implementations, one or more flexible section(s) and/orconductive wire(s) of the conductive surface can be adjusted based, atleast in part, on one or more minimums or maximums identified in thedata associated with the plasma etch process. For example, to addressthe maximum 902 identified in azimuthal profile 900, at least a portionof the conductive wire(s) 408 (and/or the flexible section 208) can beadjusted (e.g., via an adjustment mechanism) to increase and/or decreasethe distance 402 between the conductive wire(s) 408 (and/or the flexiblesection 208) and the inductive element 108. In this way, in addition toand/or instead of moving the peripheral edges of the conductive surface110, the conductive wire(s) 408 (and/or the flexible section 208) canmove relative to the inductive element 108, thereby creating a similareffect. In some implementations, (802) to (806) can be repeated in anattempt to achieve a desired uniformity and/or azimuthal profile.

While the present subject matter has been described in detail withrespect to specific example embodiments thereof, it will be appreciatedthat those skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

1-20. (canceled)
 21. A plasma processing apparatus, comprising: acylindrical dielectric window defining a plasma processing chamber; aplasma generating coil disposed about the dielectric window, the plasmagenerating coil operable to generate a plasma in the plasma processingchamber when energized with RF energy; and a conductive surface disposedadjacent the plasma generating coil, and wherein a first azimuthalportion of the conductive surface is located a first distance from theplasma generating coil and a second azimuthal portion of the conductivesurface is located a second distance from the plasma generating coil toprovide an asymmetric azimuthal profile so as to generate an azimuthallyvariable inductive coupling between the conductive surface and theplasma generating coil when the plasma generating coil is energized;wherein the first distance is different than the second distance. 22.The plasma processing apparatus of claim 21, comprising a Faraday shielddisposed between the plasma generating coil and the cylindricaldielectric window.
 23. The plasma processing apparatus of claim 21,wherein the conductive surface is wrapped around the plasma generatingcoil.
 24. The plasma processing apparatus of claim 21, wherein theplasma generating coil and the conductive surface are disposed in an RFcage.
 25. The plasma processing apparatus of claim 21, wherein theconductive surface is configured to generate an asymmetric disturbanceto the coupling between the plasma generating coil and the plasma. 26.The plasma processing apparatus of claim 21, wherein the dielectricwindow comprises quartz.
 27. The plasma processing apparatus of claim21, wherein at least a portion of the conductive surface is movablerelative to the plasma generating coil.
 28. The plasma processingapparatus of claim 21, wherein the conductive surface is grounded. 29.The plasma processing apparatus of claim 22, wherein the Faraday shieldis configured to reduce capacitive coupling between the plasmagenerating coil and the plasma.
 30. The plasma processing apparatus ofclaim 22, wherein the plasma generating coil is a cylindrical plasmagenerating coil.
 31. The plasma processing apparatus of claim 21,wherein the first azimuthal portion of the conductive surface is benttowards the plasma generating coil.
 32. The plasma processing apparatusof claim 21, wherein the first azimuthal portion of the conductivesurface is tilted towards the plasma generating coil.
 33. The plasmaprocessing apparatus of claim 21, further comprising an adjustmentmechanism operable to move the first azimuthal portion of the conductivesurface relative to the plasma generating coil.